| Keywords |
tower climbing exercise ; bone metabolism ; bone mineral density(BMD) ; rats |
| Abstract |
In general it is thought that mechanical loading through exercise increases and maintains bone mass. However, site differences in change of bone mineral density (BMD) by resistance exercise are unclear. The aim of this study was to evaluate the changes of BMD between the upper and lower limb induced by tower climbing exercise. This study was investigated effects of 12 weeks resistance exercise by tower climbing an incline on the change of upper and lower limb BMD in growing rats. Twelve male Fisher 344(F344) rats (aged 8 weeks) were divided into two group: control rats (CON, n=6) and tower climbing exercise rats (EXE, n=6). EXE group performed training that climbed the ladder at 8 times a day, 5day a week for 12 weeks. After experimental period, rats were sacrificed and femur and humerus were removed, and bone mineral density (BMD) and content (BMC) were measured by dual energy X-ray absorptionmetry (DEXA, Lunar DPXL, USA). Serum calcium (Ca), phosphate (P) and osteocalcin (OC) were determined by biochemical markers of bone metabolism. The statistical difference on the results was analyzed by independent t-test. As the results, although humerus, upper limb, BMD and BMC of EXE group showed no significant difference, femoral, lower limb, BMC (p< .05) and BMD (p< .001) of EXE group were significantly increased comparing CON group, respectively. The serum Ca, P and OC showed no significantly difference among groups. On the other hand, although femur BMD showed a significant positive correlation with OC (p< .05), there were not relationship between femur and humerus BMD (NS). These data suggested that increase of BMD by resistance exercise with climbing the ladder was appeared in only weight-bearing lower limb, namely this change of BMD might occur by site-specific. |